package tw.idv.gasolin.pycontw2012.util;

import android.util.Log;

public class SparseArray<E> {

    protected static final Object DELETED = new Object();
    protected boolean mGarbage = false;

    /**
     * Creates a new SparseArray containing no mappings.
     */
    public SparseArray() {
        this(10);
    }

    /**
     * Creates a new SparseArray containing no mappings that will not require
     * any additional memory allocation to store the specified number of
     * mappings.
     */
    public SparseArray(int initialCapacity) {
        initialCapacity = ArrayUtils.idealIntArraySize(initialCapacity);

        mKeys = new int[initialCapacity];
        mValues = new Object[initialCapacity];
        mSize = 0;
    }

    /**
     * Gets the Object mapped from the specified key, or <code>null</code> if no
     * such mapping has been made.
     */
    public E get(int key) {
        return get(key, null);
    }

    /**
     * Gets the Object mapped from the specified key, or the specified Object if
     * no such mapping has been made.
     */
    public E get(int key, E valueIfKeyNotFound) {
        int i = binarySearch(mKeys, 0, mSize, key);

        if ( i < 0 || mValues[i] == DELETED ) {
            return valueIfKeyNotFound;
        } else {
            return (E) mValues[i];
        }
    }

    /**
     * Removes the mapping from the specified key, if there was any.
     */
    public void delete(int key) {
        int i = binarySearch(mKeys, 0, mSize, key);

        if ( i >= 0 ) {
            if ( mValues[i] != DELETED ) {
                mValues[i] = DELETED;
                mGarbage = true;
            }
        }
    }

    /**
     * Alias for {@link #delete(int)}.
     */
    public void remove(int key) {
        delete(key);
    }

    protected void gc() {
        // Log.e("SparseArray", "gc start with " + mSize);

        int n = mSize;
        int o = 0;
        int[] keys = mKeys;
        Object[] values = mValues;

        for ( int i = 0; i < n; i++ ) {
            Object val = values[i];

            if ( val != DELETED ) {
                if ( i != o ) {
                    keys[o] = keys[i];
                    values[o] = val;
                }

                o++;
            }
        }

        mGarbage = false;
        mSize = o;

        // Log.e("SparseArray", "gc end with " + mSize);
    }

    /**
     * Adds a mapping from the specified key to the specified value, replacing
     * the previous mapping from the specified key if there was one.
     */
    public void put(int key, E value) {
        int i = binarySearch(mKeys, 0, mSize, key);

        if ( i >= 0 ) {
            mValues[i] = value;
        } else {
            i = ~i;

            if ( i < mSize && mValues[i] == DELETED ) {
                mKeys[i] = key;
                mValues[i] = value;
                return;
            }

            if ( mGarbage && mSize >= mKeys.length ) {
                gc();

                // Search again because indices may have changed.
                i = ~binarySearch(mKeys, 0, mSize, key);
            }

            if ( mSize >= mKeys.length ) {
                int n = ArrayUtils.idealIntArraySize(mSize + 1);

                int[] nkeys = new int[n];
                Object[] nvalues = new Object[n];

                // Log.e("SparseArray", "grow " + mKeys.length + " to " + n);
                System.arraycopy(mKeys, 0, nkeys, 0, mKeys.length);
                System.arraycopy(mValues, 0, nvalues, 0, mValues.length);

                mKeys = nkeys;
                mValues = nvalues;
            }

            if ( mSize - i != 0 ) {
                // Log.e("SparseArray", "move " + (mSize - i));
                System.arraycopy(mKeys, i, mKeys, i + 1, mSize - i);
                System.arraycopy(mValues, i, mValues, i + 1, mSize - i);
            }

            mKeys[i] = key;
            mValues[i] = value;
            mSize++;
        }
    }

    /**
     * Returns the number of key-value mappings that this SparseArray currently
     * stores.
     */
    public int size() {
        if ( mGarbage ) {
            gc();
        }

        return mSize;
    }

    /**
     * Given an index in the range <code>0...size()-1</code>, returns the key
     * from the <code>index</code>th key-value mapping that this SparseArray
     * stores.
     */
    public int keyAt(int index) {
        if ( mGarbage ) {
            gc();
        }

        return mKeys[index];
    }

    /**
     * Given an index in the range <code>0...size()-1</code>, returns the value
     * from the <code>index</code>th key-value mapping that this SparseArray
     * stores.
     */
    public E valueAt(int index) {
        if ( mGarbage ) {
            gc();
        }

        return (E) mValues[index];
    }

    /**
     * Given an index in the range <code>0...size()-1</code>, sets a new value
     * for the <code>index</code>th key-value mapping that this SparseArray
     * stores.
     */
    public void setValueAt(int index, E value) {
        if ( mGarbage ) {
            gc();
        }

        mValues[index] = value;
    }

    /**
     * Returns the index for which {@link #keyAt} would return the specified
     * key, or a negative number if the specified key is not mapped.
     */
    public int indexOfKey(int key) {
        if ( mGarbage ) {
            gc();
        }

        return binarySearch(mKeys, 0, mSize, key);
    }

    /**
     * Returns an index for which {@link #valueAt} would return the specified
     * key, or a negative number if no keys map to the specified value. Beware
     * that this is a linear search, unlike lookups by key, and that multiple
     * keys can map to the same value and this will find only one of them.
     */
    public int indexOfValue(E value) {
        if ( mGarbage ) {
            gc();
        }

        for ( int i = 0; i < mSize; i++ )
            if ( mValues[i] == value )
                return i;

        return -1;
    }

    /**
     * Removes all key-value mappings from this SparseArray.
     */
    public void clear() {
        int n = mSize;
        Object[] values = mValues;

        for ( int i = 0; i < n; i++ ) {
            values[i] = null;
        }

        mSize = 0;
        mGarbage = false;
    }

    /**
     * Puts a key/value pair into the array, optimizing for the case where the
     * key is greater than all existing keys in the array.
     */
    public void append(int key, E value) {
        if ( mSize != 0 && key <= mKeys[mSize - 1] ) {
            put(key, value);
            return;
        }

        if ( mGarbage && mSize >= mKeys.length ) {
            gc();
        }

        int pos = mSize;
        if ( pos >= mKeys.length ) {
            int n = ArrayUtils.idealIntArraySize(pos + 1);

            int[] nkeys = new int[n];
            Object[] nvalues = new Object[n];

            // Log.e("SparseArray", "grow " + mKeys.length + " to " + n);
            System.arraycopy(mKeys, 0, nkeys, 0, mKeys.length);
            System.arraycopy(mValues, 0, nvalues, 0, mValues.length);

            mKeys = nkeys;
            mValues = nvalues;
        }

        mKeys[pos] = key;
        mValues[pos] = value;
        mSize = pos + 1;
    }

    protected static int binarySearch(int[] a, int start, int len, int key) {
        int high = start + len, low = start - 1, guess;

        while ( high - low > 1 ) {
            guess = ( high + low ) / 2;

            if ( a[guess] < key )
                low = guess;
            else
                high = guess;
        }

        if ( high == start + len )
            return ~ ( start + len );
        else if ( a[high] == key )
            return high;
        else
            return ~high;
    }

    protected void checkIntegrity() {
        for ( int i = 1; i < mSize; i++ ) {
            if ( mKeys[i] <= mKeys[i - 1] ) {
                for ( int j = 0; j < mSize; j++ ) {
                    Log.e("FAIL", j + ": " + mKeys[j] + " -> " + mValues[j]);
                }

                throw new RuntimeException();
            }
        }
    }

    protected int[] mKeys;
    protected Object[] mValues;
    protected int mSize;

}
